Article transport facilities of a ceiling installation type are installed, for example, in ceiling portions of clean rooms to transport, as articles, containers for housing and carrying substrates, such as semiconductor substrates. And, in such an article transport facility, diverging portions and converging portions are provided in travel paths to allow article transport vehicles to travel in various configurations. For example, a diverging portion and a converging portion are provided in the travel path to allow the article transport vehicle to travel by providing, e.g., a U-shaped travel path that diverges, or branches off, from a loop-shaped travel path and that extends by way of carry-in-and-out portions of a plurality of substrate processing devices which perform different processes on the substrates, and that then converges or merges again into the loop-shaped travel path.
Article transport vehicles commonly have an article grip portion which can be raised and lowered, or moved vertically. And the article grip portion is vertically moved when transferring an article to or from a carry-in-and-out portion of a substrate processing device with the article transport vehicle stopped at a location that corresponds to the carry-in-and-out portion of the substrate processing device.
An article transport facility of a ceiling installation type is disclosed in JP Publication Of Application No. 2002-37059 (Patent Document 1) in which a travel path is provided to include a two-directional (or two-pronged) diverging portion that has a straight forward path and a diverging path that diverges, or branches off, toward right or left. It is also possible to provide a travel path with a two-directional converging portion including a straight forward converging path and a converging path that converges or merges from right or left using, for example, the same configuration as in the two-directional diverging portion.